﻿using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        private string firstNumber = "";
       private string  d = "";
        public Form1()
        {
            InitializeComponent();
        }

       
        private void button3_Click(object sender, EventArgs e)
        {
            

            firstNumber = textBox1.Text;
            d = textBox1.Text = "*";
            textBox1.Text = ""; 
        }

        private void button1_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + "1";
        }

        private void button4_Click(object sender, EventArgs e)
        {
 
 textBox1.Text = textBox1.Text + "2";
        }

        private void button2_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text + "3";
        }

        private void button5_Click(object sender, EventArgs e)
        {
           
            textBox1.Text = textBox1.Text + "4";
        }

        private void button8_Click(object sender, EventArgs e)
        {
            int a = Convert.ToInt32(firstNumber);
            int b=Convert.ToInt32(textBox1.Text);
            if(d=="+")
            {
                Int32 v = a + b;
                textBox1.Text=Convert.ToString(v);
            }
            if (d == "-")
            {
                Int32 v = a - b;
                textBox1.Text = Convert.ToString(v);
            } if (d == "*")
            {
                Int32 v = a * b;
                textBox1.Text = Convert.ToString(v);
            } if (d == "/")
            {
                Int32 v = a / b;
                textBox1.Text = Convert.ToString(v);
            }
        }

        private void button7_Click(object sender, EventArgs e)
        {
            firstNumber = textBox1.Text;
            d=textBox1.Text="+";
            textBox1.Text=""; 

        }

        private void button6_Click(object sender, EventArgs e)
        {
            firstNumber = textBox1.Text;
            d = textBox1.Text = "-"; 
            textBox1.Text = "";
        }

        private void button9_Click(object sender, EventArgs e)
        {
            firstNumber = textBox1.Text;
            d = textBox1.Text = "/";
            textBox1.Text = "";
        }

        private void button10_Click(object sender, EventArgs e)
        {
            textBox1.Text = "";
        }
    }
}
